1. Field of the Invention
The present invention relates to a semiconductor device having an active component such as a transistor and a manufacturing method thereof.
2. Description of the Related Art
Along with the development of CMOS technology in recent years, drive capability of a transistor is increased and heat generated from the transistor has problems.
In a MOS transistor, a threshold voltage Vth is reduced by 2 mV when temperature is increased by 1° C., therefore, sub-threshold current is increased by two digits in a state of 125° C. as compared with a state of room temperature. Accordingly, temperature management is highly important in the semiconductor device.
In a high-speed logic device such as a CPU, a chip has been hitherto cooled by mounting a heat sink, a fan and so on (for example, refer to JP-A-2000-307042 (Patent Document 1).
The above method is a method of cooling the chip from the outside, which may cause increase of stand-by current, TDDB (Time Dependent Dielectric Breakdown), electromigration and the like and may cause significant troubles with respect to device reliability when the heat generation amount is further increased with progress in miniaturization.
On the other hand, in a semiconductor device formed by performing planarization by a CMP (Chemical Mechanical Polishing) method, a dummy is arranged on the surface of a semiconductor substrate because of planarization of an interlayer insulating film (for example, refer to U.S. Pat. No. 7,014,955 (Patent Document 2)).
A layer in which the dummy is arranged is a layer relating to planarization by the CMP method, which is an active region, a gate, a metal dummy and so on. The use of the dummy as an active component has not been hitherto considered.
Accordingly, a structure in which a cooling function component is arranged in a substrate itself on which the semiconductor device is formed has been devised (for example, refer to JP-A-2008-166725 (Patent Document 3)).
However, it is necessary to add a process for forming the cooling function component to the above method, which may not satisfy the admissibility of cost effectiveness.
In response to the above, there is proposed an attempt to fabricate the device having the cooling function component without positively increasing the process by using agate dummy which has not been used as the active component (for example, refer to JP-A-2001-156228 (Patent Document 4)).